Construction machines, especially compaction machines, usually include a frame and one or two vibrating drums rotatably mounted to the frame, whereby the drums compact the surfaces as the machine moves thereon. Compacting machines often include a vibration assembly that generates vibrations and transfer these vibrations via the drum to the work surface. These eccentric assemblies are used to provide vibratory impact for compaction and also sometimes for oscillation effects for some types of compaction machines. Usually a vibration assembly for compaction machines has two eccentric weights that are adjustable relative to each other to vary the amplitude of the vibrations that are generated by rotating the eccentric assembly.